'As far as our feelings
are concerned, we are locked within our own skins.' I have always
found B. F. Skinner's words to be a particularly succinct and
dramatic statement of the problem of attributing feelings to
anyone but ourselves. I have also been impressed by the fact that
although almost everyone acknowledges that this difficulty exists,
we go about our daily lives, and particularly our interactions
with other people, as though it did not. We all pay lip service to
the idea that subjective feelings are private but respond to the
people around us as though experiences of pain and pleasure were
as public as the fact that it is raining. Thank goodness that we
do. Someone who stuck rigidly to the idea that all subjective
experiences were essentially private and that there was not, and
never could be, evidence that other people experienced anything at
all would be frightening indeed. He or she would be without what
is, for most of us, perhaps the most important curb on inflicting
damage on another person: the belief that the damage would cause
pain or suffering and that it is morally wrong to cause those
experiences in other people. This is one of the cornerstones of
our ideas about what is right and what is wrong. And yet this
suffering we are so concerned to avoid is, if we are strictly
logical about it, essentially private, an unpleasant subjective
state that only we ourselves can know about, experienced by the
particular person who inhabits our own skin.

Much of our behaviour
towards other people is thus based on the unverifiable belief that
they have subjective experiences at least somewhat like our own.
It seems a reasonable belief to hold. There is enough common
ground between people, despite their obvious differences of taste
and upbringing, that we can attempt to put ourselves in other
people's shoes and to empathize with their feelings. The fact that
we can then often successfully predict what they will do or say
next, and above all the fact that they may tell us that we have
been successful in understanding them, suggests that the empathy
has not been entirely inaccurate. We can begin to unlock them from
their skins. We assume that they suffer and decide, largely on
this basis, that it is 'wrong' to do certain things to them and
'right' to do other things.

Then we come to the
boundary of our own species. No longer do we have words. No longer
do we have the high degree of similarity of anatomy, physiology
and behaviour. But that is no reason to assume that they are any
more locked inside their skins than are members of our species.
Even in the case of other people, understanding feelings is not
always easy. Different people find pleasure or lack of it in many
different ways. It takes an effort to listen and understand and to
see the world from their point of view. With other species, we
certainly have additional difficulties, such as the fact that some
animals live all their lives submerged in water or in the
intestines of bigger animals. But those difficulties are not
insuperable — merely greater. We know what most humans like to
eat, what makes them comfortable, what is frightening, from our
own experience. With other species we may have to make an effort
to find out. The purpose of this essay is to set down the sorts of
things we should be finding out if we really want to know whether
other animals are suffering or not. I shall argue that it is
possible to build up a reasonably convincing picture of what
animals experience if the right facts about them are accumulated.
This is not in any sense to deny the essentially private nature of
subjective feelings, nor to make any claims about the nature of
mental events. It is simply to say that, just as we think we can
understand other people's experiences of pleasure, pain, suffering
and happiness, so, in some of the same ways, we may begin to
understand the feelings of animals - if, that is, we are prepared
to make an effort to study their biology. Of course, we cannot
know what they are feeling, but then nor can we know
with other people. That lack of absolute certainty does not stop
us from making assumptions about feelings in other people. And,
suitably equipped with certain biological facts about the
particular species we are concerned with, nor should it with other
animals either.

A word, first, about what
the term 'suffering' actually means. It clearly refers to some
kinds of subjective experience which have two distinguishing
characteristics. First, they are unpleasant. They are mental
states we would rather not experience. Secondly, they carry
connotations of being extreme. A mild itch may be unpleasant, but
it does not constitute 'suffering' in the way that prolonged,
intense electric shocks would do. One of the problems about
suffering is that it is not a unique state. We talk about
suffering from lack of food, but also about suffering from
overeating, as well as from cold, heat, lack of water, lack of
exercise, frustration, grief and so on. Each of these states is
subjectively different as an experience and has different
physiological and behavioural consequences. Suffering from thirst
is quite different from suffering from a bereavement, yet the same
blanket term 'suffering' is used to cover them both. About the
only thing they have in common, in fact, is that they can both be
extremely unpleasant, and someone experiencing either of them
might feel a desire to be in a different state. For this reason,
defining suffering as 'experiencing one of a wide range of
extremely unpleasant subjective (mental) states' is about as
precise a definition as we are going to be able to devise. If we
were dealing with just one sort of experience - that resulting
from food deprivation, for example -we would be on much firmer
ground. We could study the physiological effects and what the
particular species did about it. We could measure hormone levels
and brain activity and perhaps come to a precise definition. But
no such simplicity exists. Animals in intensive farms have plenty
to eat and yet we still worry that they may be suffering from
something other than lack of food. Some species may suffer in
states that no human has ever dreamed of or experienced. To be on
the safe side, we will, for the moment leave the definition
deliberately broad, although we will later be in a position to be
a bit more precise.

Our task, therefore, is to
discover methods of finding out whether and in what circumstances
animals of species other than our own experience unpleasant
emotional states strong enough to warrant the term 'suffering'. It
is the very unpleasant nature of these states that forms the core
of the problem. This is what we must look for evidence of- not (to
stress the point made earlier) that we can expect direct evidence
of unpleasant experiences in another being, but we can expect to
gather indirect evidence from various sources and put it together
to make a reasonably coherent case that an animal is suffering.
There are three main sources of such evidence: its physical
health, its physiological signs and its behaviour.

Physical Health

The first and most obvious
symptom of suffering is an animal's state of physical health. If
an animal is injured or diseased, then there are very strong
grounds for suspecting that it is suffering. All guidebooks and
codes on animal care agree on how important it is to see that an
animal is kept healthy and to treat any signs of injury or disease
at once. For many species the signs of health (bright eyes, sleek
coat or feathers) as well as those of illness (listlessness, loss
of appetite, etc.) have been listed and in any case are well known
to experienced animal keepers. There may be slight problems
sometimes. Mammals that are hibernating or birds that are
incubating their eggs may refuse food and show considerable loss
of weight. These are normally signs of ill-health but in these
particular cases seem to be perfectly natural events from which
the animals subsequently emerge well and healthy. This simply
illustrates that even the 'obvious' signs of suffering, such as
physical ill-health, are not infallible and have to be taken in
conjunction with other evidence, a point we will return to later.

Another difficulty with
using physical health (or the lack of it) to decide whether or not
an animal is suffering is that it is not, of course, the disease
or injury itself which constitutes the suffering: it is the
accompanying mental state. An animal may be injured in the sense
of being physically damaged, yet show no apparent signs of pain.
The experiences of other people are very revealing here. Soldiers
can be wounded in battle but, at the time, report little or no
pain. Conversely, people complaining of severe and constant pain
can sometimes baffle their doctors because they have no signs of
tissue damage or abnormality at all. Damage to the body does not
always go with the highly unpleasant experiences we call
'suffering from pain'. Physiology is less help than one might
expect in trying to decide when injury gives rise to pain.
Although many physiologists believe that the mechanisms of pain
perception are roughly similar in humans and other mammals, the
physiological basis of the perception of pain is not well
understood for any species. It is impossible to say with any
certainty that whenever such-and-such a physiological event occurs
people always report 'That hurts!' It is known that there are
small nerve fibres all over the body which respond to painful
stimuli, but it is difficult to interpret the messages they carry.
The situation is further complicated by the existence of other
nerve fibres which come out from the brain and affect the extent
to which the messages in the pain fibres are allowed to travel up
the spinal cord into the brain. Sometimes the messages get through
and sometimes they do not, and this affects the extent to which
pain is actually felt.

While pain continues to be
a puzzle to physiologists, it would, however, be a mistake to use
this an excuse for ignoring the effect which injury often has on
animals. Mild pain may be difficult to pin down, but signs of
intense pain in both human and non-human animals are unmistakable
(they include squealing, struggling, convulsions, etc.).
Uncertainty about whether disease, injury or loss of condition do
lead to 'suffering' in a few cases should not be used to dismiss
this valuable source of evidence about unpleasant mental states in
animals. If animals show gross disturbances of health or injuries
with symptoms of pain, it is reasonable to say that they suffer.
Experiments or other tests conducted with animals which involve
deliberately making them ill, inducing deformities or maiming them
in some way can therefore be suspected of causing suffering,
unless there are good reasons (such as the fact that an animal
uses a deformed limb in an apparently normal fashion) for thinking
that it is not experiencing anything unpleasant.

Sometimes the capture and
transport of farm animals causes weight loss, injury and
physiological deterioration so severe as to lead to death. In such
circumstances the case that the animals suffered during the
journey becomes very difficult to refute. In fact, the main
difficulty with the physical ill-health criterion of suffering
lies not so much with the (somewhat remote) possibility that
animals may not suffer despite being injured or diseased as with
the opposite possibility: that they may appear to be physically
healthy and still be undergoing intensely unpleasant mental
experiences, perhaps arising from being constantly confined in a
small cage. It is this possibility - that not all mental suffering
may show itself in gross and obvious disturbance of physical
health - that has led people to look for other ways of trying to
decide when an animal is suffering.

Physiological Signs

One of the most important
of these methods, which has been gaining ground recently because
of advances in the technology now available to it, involves
monitoring the physiological processes going on inside an animal's
body. As already mentioned, some of the things which are done to
animals, such as transporting cattle in certain sorts of trucks,
do have such traumatic effects that injury and even death may
result. But even before such gross signs of suffering set in, it
may be possible to detect physiological changes within the animal
— changes in hormone level, for example, or in the ammonia content
of muscles. Changes take place within the animal even when, on the
surface, all still appears to be well. Changes in brain activity,
heart rate and body temperature can also be picked up.

'Stress' is the name given
to the whole group of physiological changes (which may also
include activation of the sympathetic nervous system and
enlargement of the adrenal glands) that take place whenever
animals are subjected to a wide range of conditions and
situations, such as over-crowding, repeated attacks by
a member of their own species and so on. One way of viewing these
physiological symptoms of stress is as part of an animal's normal
and perfectly adaptive way of responding to conditions which are
likely, if they persist, to lead to actual physical damage or
death. Thus the heart rates goes up in preparation for an animal's
escape from danger, when it will need more oxygen for its muscles
in order to do this effectively. The change in heart rate
suggested that the animal has recognized possible danger in the
form, say, of potential injury caused by the attack of a predator.
This leads to a serious difficulty in the interpretation of
physiological measurements of stress. It may be perfectly possible
to pick up a change in the level of a particular hormone or in
heart rate, but what exactly do these changes mean for the animal?
There is no justification for concluding that it 'suffers' every
time there is a bit more hormone in its blood or its heart rate
goes up slightly. On the contrary, these signs may simply indicate
that the animal is coping with its environment in an adaptive way.
Changes in brain activity may signify nothing more than that the
animal is exploring a new object in its environment. We would
certainly not want to describe an alert and inquiring animal as
'suffering'. On the other hand, when physiological disturbances
become severe (when the adrenal glands are very enlarged, for
instance) then they become the precursors of overt disease, and we
probably would want to say the animal was suffering.

The problem is to know at
precisely what stage physiological changes in the animal stop
being part of its usual adaptive response to its environment and
start indicating a prolonged or intensely unpleasant state of
suffering. The problem lies not so much in detecting the changes
as in their interpretation and in relating them to possible mental
state. At the moment this remains a major drawback. Physiological
measures, although a valuable indication of what is going on
beneath the animal's skin, do not tell us everything we want to
know about mental states.

Behaviour

A third, and very
important, source of information about suffering in animals is
their behaviour. Behaviour has the great advantage that it can be
studied without interfering with the animal in any way. (Even with
today's technology, making physiological measurements may itself
impose some sort of hardship on the animal.) Many animals display
particular signs which can, with care, be used to infer something
about their mental states. Charles Darwin recognized this when he
entitled his book about animal communication The Expression of
the Emotions in Man and
Animals.
The problem, of course, is
to crack the code and to work out which behaviour an animal uses
to signal which emotional state.

Various different
approaches have been tried. The most direct involves putting an
animal in a situation in which it is thought to 'suffer' (usually
mildly) and then observing its behaviour. For instance, if we
wanted to know how a pig behaved when it was 'suffering from fear'
or 'suffering from frustration', we might deliberately expose it
briefly to one of its predators (to frighten it) or give it a dish
of food covered with glass (to frustrate it). Its behaviour in
these circumstances would give some indication of what it does
when it is afraid or frustrated. We could then go on to an
intensive pig farm and watch the pigs there to see if they showed
similar behaviour. If they did, this would give us some grounds
for inferring that they too were afraid or frustrated.

This method does have
rather severe limitations, however. For one thing, the way a pig
expresses frustration at not being able to get at food covered
with glass may be quite different from the way it expresses
frustration at not having any nest material, so we may simply miss
out evidence of frustration through being unfamiliar with its
various forms of expression. More seriously, even if we had
correctly identified the way in which a pig expressed
'frustration' or 'fear', we would still be left with the same
problem of calibration that we encountered with other methods such
as the measurement of physiological variables. We would still not
know, in other words, how much behaviour associated with
fear or frustration has to be shown before we are justified in
saying that the animal is 'suffering'. A fox temporarily caught in
a thicket or unable to get into a henhouse may show agitated
movements which are evidence of mild frustration, but we would
hardly want to say that it is 'suffering'. But the same animal,
confined for long periods of time in a small, bare cage from which
there is no way out and performing the same backwards-and-forwards
movements over and over again, might justifiably be described as
suffering. Somewhere we want to draw the line, but it is
difficult, without some further evidence, to know where.

What this method fails to
do - indeed, what all the methods we have described so far fail to
do - is to come to grips with the really essential issue of what
we mean by suffering, to give an indication of how much what is
being done to the animal really matters to the animal itself. We
may see injury, measure physiological changes or watch behaviour,
but what we really want to know is whether the animal is
subjectively experiencing a state sufficiently unpleasant to it to
deserve the emotive label 'suffering'. Does its injury cause pain?
We need, in other words, the animal's opinion of what is being
done to it - not just whether it finds it pleasant or unpleasant
but how unpleasant.

‘Asking’ the Animals

At first sight it may seem
quite impossible even to think of trying to obtain any sensible,
scientifically based evidence on this point. We cannot ask animals
to tell us in so many words what it feels like to be inside their
skins. But even with other human beings words are not always our
most powerful source of information. We say things like, 'Actions
speak louder than words' or 'He put his money where his mouth is.'
The word 'mouthing' actually carries an implicit suspicion of'mere
words'. We are, in fact, particularly impressed by someone who
does not just say that he dislikes or disapproves of something but
shows it by taking some action and 'voting with his feet'. For all
our human reliance on words and the complexity of our languages,
we are often more impressed by what other human beings do than by
what they say. And the things that impress us most about what they
do - making choices between difficult alternatives, moving from
one place to another, foregoing a desirable commodity for a later,
larger reward - are things that many non-human animals do too.

Other animals besides
humans can make choices and express their preferences by moving
away from or towards one environment or another. They can be
taught to operate a mechanism which in some way changes their
environment for better or worse. A rat that repeatedly presses a
lever to get food or to gain access to a female is certainly
'telling' us something about the desirability, for him, of these
things. The rat which crosses an electric grid to get at a female
is telling us even more. A. P. Silverman, in an article published
in Animal
Behaviour in
1978, describes an experiment in which rats and hamsters were
certainly making their views plain enough. These animals were
being used in an experiment to study the effects of cigarette
smoke. They were kept in glass cylinders into which a steady
stream of smoke was delivered down a small tube. Many of the
animals quickly learned to use their own faeces to bung up the
tubes and block the smoke stream. It was not completely clear
whether it was the smoke itself or the draught of air that they
objected to, but it was quite clear that they disliked what was
being done to them. Words here would simply have been superfluous.

This 'asking without
words' approach has now been used in a wide variety of situations.
It is a direct way of finding out, from the animal's point of
view, what it finds pleasant or unpleasant. Choice tests, in which
animals are offered two or more alternatives, enable them to 'vote
with their feet'. For example, as I have described in an article
that appeared in
Animal Behaviour
in 1977, chickens
which have been kept in battery cages have shown clearly that they
prefer an outside run rather than a cage. These two very different
environments were presented to hens at the opposite ends of a
corridor from the centre of which they could see both
simultaneously. They were then free to walk into either one. Most
of the hens chose to go into the outside run, not the battery
cage, the first time they were given the choice. A few of the hens
chose the battery cage at first, probably because that was what
they were used to - the run was such a novel experience for them
that they did not seem to know what it was. But all they needed
was a few minutes' experience of the run, and by the second or
third time they were faced with the choice, they too chose the
run. This seems to be a fairly objective way of saying that the
hens liked the experience of being outside in a run more than they
liked being in a battery cage.

While this result is
perhaps not particularly unexpected, animals' own preferences do
sometimes produce surprises. The Brambell Committee, which
produced an important report on intensive farming in the UK in
1965, recommended that fine hexagonal wire should not be used for
the floors of battery cages on the grounds that it was thought (by
well-meaning humans) to be uncomfortable for the hens' feet. When
allowed to choose between different floor types, however, the hens
actually preferred the fine mesh to the coarser one which had been
recommended by the Committee, as B. O. Hughes and A. J. Black
reported in British Poultry Science in 1973. Other animals
that have been 'asked' their opinion of their surroundings are
laboratory mice and rats, which have shown preferences for certain
sorts of nest box and cage size; and in 1967 B. A. Baldwin and D.
L. Ingram published an article in Physiology and Behaviour on
pigs which indicated preferences for heat levels and lighting
regimes by being provided with switches which they could operate
with their snouts to regulate heat and light. Sometimes animals'
preferences result in an actual saving for the farmer. In Farm
Animal
Housing and Welfare,
edited by S. and M. Baxter
and J. MacCormack, Stan Curtis reported a study on a group of
young pigs which actually turned their heating down at night,
below the level that humans thought should be maintained all the
time, which resulted in a considerable saving in fuel. Such a
happy coincidence between what animals like and what is best for
commercial profit does not, however, always occur.

In any case, just because
an animal prefers one set of conditions to another does not
neccessarily mean that it suffers if kept in the less preferred
ones. In order to establish the link - that is, to make the
connection between preference (or lack of it) and suffering - it
is necessary to find out how strong the animal's aversion to the
less attractive situation is, or how powerfully it is attracted to
preferred conditions. If a male rat will cross a live electric
grid to get a female or a hen goes without food in order to obtain
somewhere to dustbathe, they are demonstrating that these things
are not just 'liked' but are very important to them indeed. Many
people would agree that animals suffer if kept without food or if
given electric shocks. If the animals tell us that other things
are as important as or more important to them than food or the
avoidance of shock, then we might want to say that they suffer if
deprived of these other things as well.

We have, therefore, to get
animals to put a 'price' on their preferences. Now, it is
obviously something of a problem to decide how to ask animals how
they rate one commodity, such as food, against something that may
be quite different, such as the opportunity to dustbathe, wallow
in mud or fight a rival. But the problem is not insuperable, and
one of the easiest ways to determine this is through what
psychologists call 'operant conditioning', which simply means
giving an animal the chance to learn that by pressing a lever,
say, it gets something it likes, such as a piece of food (a
reward), or can avoid something it doesn't like (a punishment).
Depending on the animal, what it has to do can vary. Birds often
find it easier to peck a disc rather than operate a lever, which a
rat would do readily, and fish, of course, would have difficulties
with either and would have to be given, say, a hoop to swim
through. Once the animal has learned to do whatever has been
devised for it, the experimenter can then begin to put up the
'price' by making the animal peck the key or press the lever not
just once but many times before it gets anything at all. In the
Netherlands J. van Rooijen reports, in an article published in
Applied
Animal Ethology
in 1983, that he has used
this method to measure the strength of the preference of pigs for
earth floors by forcing them to make a larger number of responses
in order to be allowed access to the earth.

When food is being used as
the reward, animals usually appear to be prepared to work harder
and harder for the same reward, indicating, not surprisingly, that
food is very important to them. Other commodities, however, seem
to be less important. Male Siamese fighting fish can readily be
trained to do things for the reward of being able to see and
display at a rival fish of the same species. But if the number of
responses the fish has to make for each opportunity to display at
a rival is increased, the fish do not work any harder and so
obtain a smaller number of views of their rival, according to J.
A. Hogan, S. Kleist and C. S. L. Hutchings, whose findings were
published in the Journal of Comparative and Physiological
Psychology in 1970. A similar result has been reported for
cocks pecking at keys for food and for the sight of another cock.
When the number of pecks required for each presentation (bit of
food or sight of a rival) went up, the birds would work much
harder for food than to see their rival. Access to a rival seemed
in both these examples to be less important to the animals than
food.

An Objective Measure of
Suffering

There are, then, ways of
obtaining measures of how much an animal prefers or dislikes
something. Here is the key to discovering the circumstances in
which an animal finds things so unpleasant that we want to say
that it is suffering. If it will work hard to obtain or to escape
from something — as hard as or harder than it will work to obtain
food which most people would agree is an essential to health and
welfare — then we can begin to compile a list of situations which
cause suffering and, indeed, can arrive at a tentative further
definition of suffering itself: animals suffer if kept in
conditions in which they are without something that they will work
hard to obtain, given the opportunity, or in conditions that they
will work hard to get away from, also given the opportunity.
'Working hard' can be given precise meaning, as explained earlier,
by putting up the 'price' of a commodity and seeing how much it is
worth to the animal. We have then the animal's view of its
environment.

Of course, we have to make
one important assumption: that if animals are prepared to work
hard in this way, they do experience a mental state which is
'pleasant' if something is rewarding and 'unpleasant' if they are
trying to avoid that something. We have, in other words, to make a
leap from inside our own skins to the inside of theirs. But this
leap is a very bare minimum. It does not assume that other animals
find the same things pleasant or unpleasant as we do, only
that working to obtain or working to avoid something is an
indication of the presence of these mental states and that working
hard is an indication that they are very pleasant or very
unpleasant. Exactly what other animals find very pleasant or very
unpleasant is left to experimental tests. In other words, the leap
that we have to make from our skins to theirs takes into account
the possibility that their suffering or their pleasure may be
brought about by events quite different from those that cause them
in us. We are not imagining ourselves shut up in a battery cage or
dressed up in a bat suit when we try to find out what it is like
to be a hen or a bat; we are trying to find out what it is like to
be them. There is a lot of difference between the two. In
the first case we would see animals as just like us, only with fur
or feathers. In the second case we acknowledge that their view of
the world may be very different from our own, that their
requirements and what makes them comfortable or uncomfortable may
be nothing like what we ourselves would require. We then have to
get down to the business of finding out what their view of the
world really is. Operant conditioning may be the key, the window
on to their world, but it takes quite a lot of effort to get all
the answers we need.

Even then we are not
completely home and dry. Preference tests and operant
conditioning, though immensely valuable tools, do not provide all
the answers. A dog might show very strongly, if 'asked' in this
way, that he would rather not go to the vet. One could make out a
strong case for saying that he 'suffers' if forced to do so.
Cattle, given a free choice, do not always eat what is good for
them and may even poison themselves. It would therefore be a
mistake to use these methods in isolation from other measures of
suffering. A synthetic approach (one, that is, that takes into
account all the measures that we have discussed) is probably the
safest bet in the long run. Since each of these measures has
something to be said against it, some limits to its usefulness,
the safest approach is therefore to make as many different sorts
of measurement as we can and then to put them together to see what
sort of conglomerate picture we get. For example, suppose some
hypothetical animals were kept in small cages, in conditions that
were very different from those of their wild ancestors. Suppose
people had expressed considerable worry that they were suffering.
How might we go about evaluating this claim?

We might look first at the
physical health of the animals. If we found them to be very
healthy, with bright eyes and sleek, glossy coats and no signs of
injury or parasites, we might then want to proceed to other
measures. If we noticed that the animal showed a number of unusual
behaviour patterns not shown by freer animals of the same species,
the next step would be to investigate what caused them to behave
in this way. In the first case it might be that the unusual
behaviour was solely the result of the animals showing positive
reactions to their keepers. We might also find that the animals
appeared to 'like' their cages and that they would choose them in
preference to other conditions which well-meaning humans thought
they would prefer. In such circumstances our verdict might be that
although the animals were kept in highly unnatural conditions,
they did not, on any criteria, appear to be suffering as a result.
On the other hand, the conclusions might be very different even
for physically healthy animals. If the animals showed evidence of
a high degree of frustration, prolonged over much of their lives,
with evidence of a build-up of physiological symptoms that were
known to be precursors of disease, we might begin to think they
were suffering. If, in addition, they showed every sign of trying
to escape from their cages, and indeed did so when given the
opportunity, our evidence on this point would become even
stronger.

The point of these
hypothetical examples is to show how, given different sorts of
evidence, different conclusions can be reached about whether or
not animals are suffering. We have still not observed their mental
states directly. Nor have we escaped altogether from some use of
analogy with our own feelings to tell us what a member of another
species might be experiencing. In the last analysis, we have to
rely on analogy with ourselves to decide that any other being
(including another human) experiences anything at all, since our
own skin is the only one we have any direct experience of being
inside. But analogy with ourselves that relies on seeing animals
as just like human beings with fur or feathers is quite different
and much more prone to error than analogy which makes full use of
our biological knowledge of the animal concerned - the conditions
in which it is healthy, what it chooses, its behaviour and its
physiology. This second kind of analogy, the piece-by-piece
construction of a picture (What does the animal like? What makes
it healthy? What are its signs of fear or frustration?), is hard
work to construct, as it needs a lot of basic research on each
kind of animal with which we might come into contact. But it is
the only kind of analogy which, in the end, will give us any real
hope of being able to unlock other species from their skins and of
beginning to see the world through not just our eyes but theirs as
well.